The present invention relates to a bearing device for receiving axial force of a crankshaft of an internal combustion engine.
A crankshaft of an internal combustion engine is rotatably supported at its journal portion by a cylinder block lower portion of the internal combustion engine via a main bearing which is configured by combining a pair of half bearings into a cylindrical shape.
One or both of the pair of half bearings are used by being combined with a half thrust bearing(s) which receives the axial force of the crankshaft. The half thrust bearing(s) is placed at one or both of axial end surfaces of the half bearing.
The half thrust bearing receives the axial force which occurs to the crankshaft. That is, the half thrust bearing is disposed for the purpose of supporting the axial force which is inputted into the crankshaft when the crankshaft is connected with a transmission by a clutch or the like.
On slide surface sides in vicinities of both circumferential ends of the half thrust bearing, thrust reliefs are formed so that the thickness of a bearing member becomes thinner toward a circumferential end surface. In general, the thrust relief is formed so that the length from the circumferential end surface of the half thrust bearing to the slide surface and the depth at the circumferential end surface are constant irrespective of the position in a radial direction. The thrust relief is formed to absorb a positional deviation of the end surfaces of a pair of half thrust bearings at when the half thrust bearings are assembled into a divided type bearing housing (see FIG. 10 of JP-A-H11-201145).
The crankshaft of the internal combustion engine is supported at its journal portion by the cylinder block lower portion of the internal combustion engine via the main bearing formed by a pair of half bearings. At this time, lubricating oil is fed into a lubricating oil groove which is formed along an inner circumferential surface of the main bearing through a through-port in a wall of the main bearing, from an oil gallery in a cylinder block wall. The lubricating oil is supplied into the lubricating oil groove of the main bearing in this way, and thereafter is supplied to the half thrust bearing. Note that for the thrust bearing which receives the axial force of the crankshaft of the internal combustion engine, a laminated structure in which an aluminum bearing alloy layer or a copper bearing alloy layer is formed on one surface of a back metal layer of an Fe alloy is generally used.
Incidentally, in recent years, oil pumps of internal combustion engines for supplying lubricating oil are downsized, and therefore the amount of the lubricating oil supplied to bearings have decreased. Accordingly, the amount of leakage of the lubricating oil from the end surfaces of the main bearings also decrease, and therefore the amount of the lubricating oil supplied to the half thrust bearings tends to decrease. As countermeasures against this, there is proposed an art of enhancing oil retentivity for lubricating oil by forming a plurality of fine grooves side by side on the slide surface of the half thrust bearing, for example (see to JP-A-2001-323928).